Thermal-sensitive recording methods are advantageous in that (1) development is not necessary, (2) when the support is made of paper, the support is similar in quality to paper for general use, (3) treatment is easy, (4) the developed color density is high, (5) the recording apparatus is simple and inexpensive, and (6) noise is not produced in recording. The uses thereof have therefore been expanded in the field of facsimile and printers, and in the field of labels such as POS (point-of-sale). Accordingly, the demand for thermal-sensitive recording materials is diverse, and thermal-sensitive recording materials for multicolor recording and transparent thermal-sensitive recording materials for overhead projectors have also been developed as described, for example, in JP-A-63-265682 (the term "JP-A" as used herein means an "unexamined published Japanese patent application").
With recent electronic developments in medical instruments such as ultrasonic scanners, CT scanners and X-ray apparatuses, transparent thermal-sensitive recording materials have also been developed which can directly record the digital images of these instruments. In this case, when doctors, etc. conduct medical examinations, images recorded on the thermal-sensitive recording material are generally illuminated with the light of a fluorescent lamp, etc. from the backside thereof behind (such an illuminating device is called a light box) to observe the images from the support side so as not to damage the images.
However, when images recorded on a conventional thermal-sensitive recording material in which a thermal-sensitive recording layer is formed on a transparent support is observed on the light box from the support side, the following problems are encountered. First, the light of the light box passing through transparent non-image portions produces illusion, resulting in indistinct images which seem to be different from as it is. Such indistinct images are undesirable because they are in danger of causing to be made a wrong diagnosis (e.g., diagnosing a non-morbid portion as morbid, or the other way about). Second, a smooth surface of the transparent support (a side on which the thermal-sensitive recording layer is not formed) causes high luster of the images, which tends to tire the eye.